1. Field of the Invention
The present invention concerns a high-tension circuit-breaker having an interrupter chamber filled with insulative gas in which are disposed a fixed assembly comprising contacts for the passage of the permanent current and arc contacts and a mobile assembly comprising contacts for the passage of the permanent current, arc contacts and a gas blast cylinder associated with a gas blast nozzle. The mobile assembly is connected to an operating mechanism by an insulative rod.
The mobile assembly has a relatively high total mass which, during an operation to open the circuit-breaker, is driven at high speed over a relatively short travel. The high speed is imposed by the need to extinguish the arc rapidly on the first zero-crossing of the current and to move the contacts quickly apart to avoid all risk of restriking of the arc.
It is essential for the movement of the mobile assembly to be damped at the end of its travel, failing which the pole may be damaged or premature wear may occur.
2. Description of the Prior Art
Most known circuit-breaker damper devices include a cylinder filled with gas compressed by a piston attached to the mobile assembly. In such systems, the damping force is low at the start of damping and becomes very high at the end of damping, which often causes the mobile contacts of the circuit-breaker to rebound.
One aim of the present invention is to provide a circuit-breaker in which the damping force is high from the very start of damping, without reaching a value that can cause rebound.